Figure 2.

Effect of sleep duration on leptin and ghrelin levels. a | Mean (±SEM) leptin and serum plasma ghrelin levels in healthy individuals after 2 days with 4 h or 10 h sleep periods. b | Mean (SEM) 24 h serum leptin profiles after 6 days of 4 h, 8 h and 12 h in bed in nine healthy, lean men, studied at bed rest who ate three identical carbohydrate-rich meals. At the end of these study periods, the participants slept an average of 3 h 48 min in the 4 h in bed group, 6 h 52 min in the 8 h in bed group, and 8 h 52 min in the 12 h in bed group. All characteristics of the 24 h leptin profile increased from the 4 h to the 12 h bedtime condition. The bars represent sleep periods. Permission for panel a was obtained from the American College of Physicians © Spiegel K et al. Brief communication: sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann. Intern. Med. 141, 846–850 (2004). Permission for panel b was obtained from The Endocrine Society © Spiegel K et al. Leptin levels are dependent on sleep duration: relationships with sympathovagal balance, carbohydrate regulation, cortisol, and thyrotropin. J Clin. Endocrinol. Metab. 89, 5762–5771 (2004).